Abstract
Tapping panel dryness (TPD) syndrome is one of the latex yield affecting factors in the rubber tree (Hevea brasiliensis Mull. Arg.). Therefore, identification of a DNA marker will be highly useful for screening progenies in breeding programs. The major goal of this study was to detect genetic variations and/or identification of gene fragments among 37 Hevea clones by the random amplified polymorphic DNA “fingerprinting” technique. Different levels of DNA polymorphism were detected with various primers and a distinct polymorphic band (2.0 kb) was obtained with OPA-17 primer. It was cloned into a plasmid vector for further sequence characterization and the nucleotide sequence shows homology with a novel putative plant thymidine kinase (TK) gene, designated as HbTK (Hevea brasiliensis thymidine kinase; GenBank accession number AY130829). The protein HbTK has 67%, 65%, 64%, and 63% similarity to TK genes of Medicago, Oryza, Arabidopsis, and Lyco-persicon, respectively, and it was highly conserved in all species analyzed. The predicted amino acid sequence contained conserved domains of TK proteins in the C-terminal half. Southern blot analysis indicated that HbTK is one of the members of a small gene family. Northern blot results revealed that the expression of the HbTK gene was up-regulated in mature bark tissues of the healthy tree while it was down-regulated in the TPD-affected one. These results suggest that this gene may play important roles in maintaining active nucleotide metabolism during cell division at the tapped site of bark tissues in the healthy tree under stress (tapping) conditions for normal latex biosynthesis.
Highlights
Natural rubber is produced in latex at the expense of high energyKey words: cloning, Hevea brasiliensis, random amplified polymorphic DNA fingerprints, rubber tree, tapping panel dryness, thymidine kinase gene.Perumal Venkatachalam,[1] Natesan Geetha, Padmanabhan Priya,[2] Arjunan Thulaseedharan cost, and is considered as a secondary metabolite with no known function in plant cells
This paper reports identification, cloning, and sequence characterization of a polymorphic band, and its expression pattern is correlated between healthy and Tapping panel dryness (TPD)-affected rubber trees to consider it as a potential molecular marker for the detection of the TPD syndrome
The labeled blots were tive, early DNA diagnostic system to implemid DNA was carried out from five independ- exposed to X-ray film (X-Omat, Kodak) with ment marker-assisted selection (MAS) in ent transformed clones using a mini prepar- intensifying screens at -80°C for 1-3 days
Summary
Natural rubber (cis-1,4-polyisoprene) is produced in latex at the expense of high energy. 67%, 65%, 64%, and 63% similarity to TK genes rubber tree, tapping panel dryness (TPD) is as RAPD markers to study inter- and intra-speof Medicago, Oryza, Arabidopsis, and Lyco- one of the important syndromes that greatly cific genetic variation[11] for the identification of persicon, respectively, and it was highly con- affect the latex yield. This paper reports identification, cloning, and sequence characterization of a polymorphic band, and its expression pattern is correlated between healthy and TPD-affected rubber trees to consider it as a potential molecular marker for the detection of the TPD syndrome. ALF tolerance, TPD severe High yield, ALF susceptible, TPD susceptible Average yield, TPD mild, PM severe, ALF low
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